Charge loader device, system, and method for underwater seismic exploration

ABSTRACT

A device for loading small explosive charges for delivery to an underwater seismic shooting site over prolonged periods with greater regularity of sequence and higher rate of delivery than possible heretofore is provided which comprises a housing, and an open passageway extending therethrough and including a constricted throat portion and an adjacent frustoconical expansion section together with means for conveying fluid into the throat for generation of Venturi type pressure lowering as the source of suction force for drawing the small charges, inserted into the open passageway end, through the throat and expansion section for delivery to the site. Method and system (1) for such loading of small charges, (2) for firing said charges and (3) for measurement of resulting seismic disturbances for a seismic record, are also provided.

United States Patent 3,360,070 12/ 1967 Choletetal.

Richard R. Larson Ulster Park, N.Y.

Nov. 4, 1969 May 1 1, 197 1 Hercules Incorporated Wilmington, Del.

Continuation-impart of application Ser. No. 818,475, Apr. 21, 1969.

inventor Appl. No Filed Patented Assignee CHARGE LOADER DEVICE, SYSTEM,AND METHOD FOR UNDERWATER SEISMIC EXPLORATION 22 Claims, 8 Drawing Figs.

US. Cl 181/.5XC Int. Cl F421! 3/06 Field of 102/21,

References Cited UNITED STATES PATENTS 3,496,532 2/1970 Thigpenl8l/.5(XC) Primary ExaminerVerlin R. Pendegrass AttorneyS. Grant Stewartthe small charges, inserted into the open passageway end,

through the throat and expansion section for delivery to the site.

Method and system (1) for such loading of small charges, (2) for firingsaid charges and (3) for measurement of resulting seismic disturbancesfor a seismic record, are also provided.

I A'o 78o s 9 CHARGE STORAGE 79 (X 82 BI 82 I 8 82 82 82 37 l l I ll 4D4 D4 l l l PATENTED Mn 1 m 3579.101

SHEET 1 OF 2 FIG. 2A

RICHARD R. LARSON INVENTOR ATTORNEY PATENTED MAY] 1 IQYI SHEET 2 UF 2'E'unum 2mm FIG.5

CHARGE STORAGE WATER PUMP I70 78b 24c FIG.6

FIG. 7

RICHARD R. LARSON INVENTOR ATTORNEY CHARGE LOADER DEVICE, SYSTEM, ANDMETHOD FOR UNDERWATER SEISMIC EXPLORATION This application is acontinuation-in-part of my copending application Ser. No. 818,475 filedApr. 21, 1969.

This invention relates to a device for sequentially loading smallexplosive charges for delivery to an underwater seismic shooting site.In one aspect this invention relates to a system, including such loaderdevice, for loading small explosive charges for delivery to anunderwater seismic shooting site; and, in another aspect, to system forloading the charges and delivery and firing of same for generation ofseismic energy in the underwater seismic test area. In another aspectthis invention relates to a method for loading small charges fordelivery to an underwater seismic shooting site; and, in a furtheraspect, to a method for loading the charges and delivering and firingsame for generation of seismic energy in the test area. In still otheraspects, this invention relates to seismic exploration method and systemabove referred to for loading, delivering and firing the charges, andmeasuring the resultant seismic energy for a seismic record. Otheraspects will be apparent in light of the accompanying disclosure and theappended claims.

Seismic exploration involves the introduction of energy'into the earthto initiate wave action for determination of subsurface structurecharacteristics, and is based on the generation of seismic disturbances,or waves, in the earths surface which are reflected or refracted fromvaried strata interfaces and the like.

ln off-shore seismic exploration, utilizing an explosive as the energysource, general technique has involved assembly of the charge on deck ofa boat moving through the seismic test area and emplacement of theassembled charge from the moving boat. Until recently, large seismiccharges of both the high explosive and nitrocarbonitrate (NCN) type,often in the order of from to 50 pounds, have been utilized. Howeverhigh explosives of any size are often unsuitable from the standpoint offish kill and safety hazards involved and, even large NCN charges have,at times, presented serious fish kill problems. Further, the largercharges, upon detonation, have often imparted damage to the adjacentimmersed seismic test equipment; and on-deck manpower, and storage,requirements have been high. Consequently, the industry has turned tothe use of small seismic charges, generally NCNs of say from one-half to4 pounds.

As will be readily appreciated, the use of such small charges ascompared with that of the larger charges has required emplacement anddetonation of a proportionately larger number of charges in a given testarea which in turn has required emplacement and shooting of charges morerapidly than required in earlier practice.

1n the copending US. applications Ser. Nos. 673,594 filed Oct. 9, 1967,and now abandoned, 724,942 filed Apr. 29, 1968, parent 818,475 filedApr. 21, 1969, and now Pat. No. 3,509,820 and 818,476 filed Apr. 21,1969, are disclosed seismic exploration systems utilizing smallexplosive charges, as a seismic energy source, in conjunction withunderwater firing and associated charge loading means.

Heretofore a conventional breech type device has been utilized in thesystems of the above referred to copending applications, for loading thecharges for delivery to the firing station. One such breech type loaderhas been a chamber open at one end and having a quick acting inlet valveat the other end, and a hinged top. In the operation of that device itis generally required that one operator man the valve to regulate waterflow into, and through the chamber and that another operator open thehinged top, insert the charge and close the top to thus synchronizeoperation of the chamber top and insertion of the charge with alternateclosing and opening of the valve for regulation of water ingress as adriving force for moving the charge from the chamber for delivery to thefiring device. Accomplishment of acceptable loading utilizing thatparticular mechanism requires the carefully coordinated action of twooperators, nevertheless with limitations in loading rate and regularityof loading sequence. Another such conventional breech type loadingsystem has been proposed, in' which two chambers are connected inparallel in a water stream, and a single cross slide, containing twoholes, extends across the two chambers so as to alternately position onehole, or passageway, in one chamber to admit water flow therethroughwhile the other passageway is outside the other chamber with the slidein closing relationship therewith. In this manner, the slide is operatedto alternately close one chamber, and open the other, to facilitatealternate loadings for delivery of the charge to the shooting site. Suchloading device requires an assembly of moving parts, water sealmaintenance, remote power for operation of the slide system, all withattendant disadvantages in respect of rate and regularity of loadingsequence.

This invention is concerned with a loader assembly, or

device, for sequentially loading small explosive charges for delivery toan underwater seismic shooting site, and which operates without movingparts and can be operated by one operator over a prolonged period withmarkedly greater regularity of sequence and higher rate of delivery thanpossible heretofore. The invention is also concerned with method, andsystem, for loading the charges, and in separate embodiments, fordelivery and firing the loaded charges, and for measuring the resultantseismic energyeach system containing a loader device of the invention.

In accordance with the invention, a device is provided for sequentiallyloading small explosive charges for delivery to an underwater seismicshooting site, comprising a housing; a passageway extending through saidhousing for successively conveying said charges, and said passagewayvhaving a constricted cross section along part of its length, as a throatportion; a section of said passageway diverging from said throatportion; and means for conveying fluid into said throat portion and forpassing same through said throat portion under high velocity conditionsin a direction toward said diverging section.

The cross-sectional dimensions of the passageway are predetermined forconveying the small charges through it for delivery to the shootingsite. By way of example, the small seismic charges presently utilizedare generally cylindrical and have a length in the order of from about 4/2 to 5 inches and a diametric cross section of from about 2 to 2%inches. The throat portion of the passageway is generally cylindricaland is often from about 2% to 6 inches in length by about 2% to 2 /2inches in diameter, and the diverging section is a frusto cone of from12 to 13 inches in length having an angle of divergence of from about 1%to 2 half angle. Any remaining, and rearward most section, of thepassageway, which serves as a port," or a receiving zone, is anysuitable dimension for receiving the charge assemblies for travel to thethroat.

The above described means for conveying fluid into the throat sectioncan be a plurality of separate passageways extending through the housingwall and into open communication with the throat section on the throatperiphery. However now preferred, and described more fully withreference to the drawings herein, is an open channelway extending alongthe entire periphery of the throat portion. The fluid delivery capacityof the channelway is generally variable for any given loading.

The loading assembly is operated by passing a suitable fluid into thethroat portion at sufficiently high velocity to concurrently generate aVenturi effect within the throat, with accompanying reduction inpressure therein. The reduced pressure thus generated in the throatcreates a force of suction through the upstream end of the throat suchthat when the explosive charge is inserted into the throat, upstreamfrom the point of fluid ingress, it moves into the throat in response tothat suction force, ie the pressure differential between that outsidethe throat and the throat interior, to thus move into the throat andinto the path of the forwardly moving high velocity fluid. In thismanner, the high velocity moving fluid impinges against the chargeassembly moving through the throat to thus provide further force formoving the charge in entrainment with the forwardly moving fluid, intothe diverging, or expansion, section of the passageway wherein, due tothe lowered water velocity, the pressure is correspondingly higher fordischarge of the water, and charge carried therein, for delivery to theshooting site.

Further, in accordance with the invention, a system, including a chargeloader device of the invention, is provided for loading seismic chargesfor delivery to an underwater firing station, which comprises a chargeloading station remote from said firing station, and a seismic explosivecharge loader assembly at said loading station; said loader assemblycomprising (1) a housing, (2) a passageway extending through saidhousing for successively conveying said charges, and said passagewayhaving a constricted cross section along part of its length, as a throatportion, (3) a section of said passageway diverging from said throatportion, (4) means for conveying fluid into said throat portion and forpassing same through said throat portion under high velocity flowconditions in a direction toward said diverging section, and (5) meansfor communicating said passageway through said diverging section withconduit means for delivering explosive charges from said loader assemblyto said firing station; and means for delivering water, as said fluid,through said conveying means for said fiow through said throat.

The invention further provides a system for underwater seismic shootingutilizing small explosive charges as the seismic energy source andincluding a charge loader device of the invention, which comprises asubmersed firing station for firing said charges; a seismic chargeloader remote from said firing station and comprising l a housing, (2) apassageway extending through said housing for successively conveyingsaid charges, and said passageway having a constricted cross sectionalong part of its length, as a throat portion, (3) a section of saidpassageway diverging from said throat portion, and (4) means forconveying fluid into said throat portion and for passing same throughsaid throat portion under high velocity fiow conditions in a directiontoward said diverging end; means for delivering fiuid through saidconveying means for said high velocity flow; conduit means connectingthe diverged end of said diverging section of said passageway with saidfiring station for conveying said charges from said loader device tosaid firing station; and means at said firing station for firing saidcharges to provide said seismic energy.

Further in accordance with the invention a method for sequentiallyloading seismic explosive charges at a charge loading station in amarine seismic area, for delivery to an adjacent underwater seismicshooting site, is provided which comprises pumping water from the marinearea at high flow velocity through a throat-way supported at saidstation in direct communication at one end with atmospheric air, andthen passing said water into and through a diverging zone of expansion,whereby the pressure in said throat becomes less than that of thesurrounding atmospheric air and air is drawn from the adjacentatmosphere into said throat through said open end; sequentiallyinserting said charges from the adjacent air atmosphere into said openend of said throat-way, whereby said charges are moved into an initialzone in said throat-way for force of air drawn from the adjacent airatmosphere and then through the remainder of said throat-way and throughsaid diverging zone under combined force of atmospheric pressure andimpinging force of said water for delivery, entrained in said water, tosaid shooting site.

The invention further provides a seismic exploration method forsequentially loading seismic explosive charges at a charge loadingstation in a marine area and delivery of the charges to an underwatershooting site and firing same to provide seismic energy for a seismicrecord, which comprises pumping water from the marine area at highvelocity through a throat-way supported at said station in directcommunication at one end with atmospheric air, and then passing saidwater into and through a diverging zone of expansion, whereby thepressure in said throat becomes less than that of the surroundingatmospheric air and air is drawn from the adjacent atmosphere into saidthroat through said open end; sequentially inserting said charges fromthe adjacent air atmosphere into said open end of said throat-way,whereby said charges are moved into an initial zone in said throat-wayby force of air drawn from the adjacent air atmosphere and then throughthe remainder of said throat-way and through said diverging zone undercombined force of atmospheric pressure and impinging force of said waterfor delivery, entrained in said water, to said shooting site; deliveringsaid charges from said diverging zone to said shooting site, and thenfiring said charges to provide said seismic energy.

The invention is further illustrated with reference to the drawings ofwhich FIG. I is a cross-sectional view of one embodiment of a chargeloader assembly of the invention; FIG. 2 is a cross-sectional view of anow preferred form of charge loader assembly, including channelway meansfor admitting fiuid under high velocity into the throat section andmeans for varying the fluid delivery capacity of the channelway; FIG. 2Ais the same as FIG. 2 except that it is devoid of the channel, andassociated structure of FIG. 2; FIG. 3 is a view, in perspective, of aloader assembly of the invention, and auxiliary equipment, for operationon a seismic boat deck; FIG. 4 is a cross-sectional view of one form ofsmall seismic charge assembly loaded for firing in accordance with theinvention; FIG. 5 is a cross-sectional view of one form of firingdevice, for firing seismic charges, loaded and delivered to the shootingsite in accordance with the invention; FIG. 6 is a diagrammaticillustration of seismic loading, and exploration systems of theinvention including, as now preferred, a loading device of FIG. 2, and afiring device of FIG. 5; and FIG. 7 is a partial view ofa loading deviceof FIG. 2 and associated port closure means for precluding suction ofair into the throat of the device during continued operation of samebetween loading periods. The drawings further illustrate method of theinvention.

Referring to FIG. 1, housing 10 of seismic charge loader 9, containselongated passageway system 11 extending therethrough and open at bothends, viz. rearward end 11 and forward end 11', and having a constrictedcross section along part of its length as a throat portion, viz. throatB described hereinafter.

Passageway Ill contains sections A, B and C coaxially disposed in seriesfor conveying small seismic charge assemblies for delivery to theshooting site. Intermediate passageway, portion, or section, B isgenerally of circular cross section and serves as a throat member forsequentially conveying the explosive charges, as more fully describedhereinafter; forward end section C is frustoconical and diverges fromthe periphery of throat portion B at the forward end b thereof, toward,and through, the forward end 10" of housing 10; and rearward end sectionA diverges from the periphery of throat section B at the rearward end athereof toward, and through, the end 10 of housing 10.

Section A, as a port," or charge receiving zone, can be of any suitablelength to facilitate direction of the seismic charges from outsidehousing 10 through section A and axially into throat B; and throat B anddiverging end section C are of any suitable length to facilitatesequential travel of the charges through the remaining sections B and Cfor delivery to the shooting site. Generally the length of section C isin a ratio to the diameter of throat B of at least 5: l.

A plurality of conduits 12 extend angularly, say at an angle of from 10to 20 with the passageway 11 axis, through a sidewall of the housinginto direct open communication with the throat B in a direction towarddischarge section C. Conduits I2 open into throat B along a peripheralpath 13 (dotted line) on the housing inner wall around throat B,intermediate the forward and rear ends thereof. Although any suitablenumber of openings I2 can be utilized, it is generally advantageous thatthe number of conduits I2 is such that the openings, on the peripheralpath I3, are not apart by more than one to three passageway I2 widths.Conduits 12 are adapted to be in open fluidtight communication with ahigh pressure fluid source for conveying fluid into throat B as aplurality of high velocity streams in a direction toward dischargesection C.

In the operation of loader assembly 9, a fluid stream is injected athigh velocity through each of the conduits 12 into throat B in adirection toward, and through end section C to thus cause a Venturi typereduction in pressure in throat section B to a level below that outsidehousing to generate a suction force in throat B drawing air from theoutside of housing 10 through section A. The fluid injected fromconduits 12 into throat B flows into discharge section C wherein thevelocity energy of the fluid-air mixture is converted to increasedpressure, and from section C through opening 11',

and into a suitable conduit (not shown) threadably secured- (threads 14)to the forward end of housing 10.

In preferred practice, the loader assembly is operated as a component ofa system, on deck of a tow boat moving through the seismic area. Water,as the fluid introduced through conduits I2, is pumped from the adjacentwater body in the seismic area, to the boat deck and through conduitsl2.Air is drawn from the atmosphere through the port section A by force ofsuction in throat B. It is necessary that the flow velocity of the waterthrough conduits 12 by regulated to provide the desired air to waterratio in throat B, for the desired degree of suction force in section A,which in turn draws air from outside the housing as a force for drivingthe added charges through section A and into the lowered pressure zonein throat B. Whether the amount of suction force is sufficient to draweach charge entirely through section A or draw it into throat B onlyafter the charge has been inserted in a forward part of section A,depends on the air to water ratio utilized. In any event, when thecharge is drawn past the water ingress points on the inner wall ofhousing 10, i.e. path 13, it is impinged by the incoming streams andthus additional force resulting from the impingement serves as furtherdriving force for moving the charges into the expansion chamber, orsection C, which converts the velocity energy of the water to higherpressure energy for discharge from housing 10.

Housing 10 can be connected at the forward end 10" by threads 14 with asuitable delivery hose, or conduit, for accepting the entire water-airmixture and seismic charge entrained therein, from forward section C fordelivery to the underwater shooting site.

The loading device of FIG. 1 is readily operated by one operator who canmerely insert the charges in section A of the device, which will thentravel through throat B and section C for delivery to the firing zone.No moving parts, seals, or additional operating manpower are requiredand hence the charges can be sequentially delivered from the assembly 9at a high degree of rate, and regularity of sequence, to provide forloading markedly improved over that accomplished heretofore.

In a now preferred embodiment of loader assembly, in accordance withwhich rate of flow of fluid into the throat can be adjusted during theloading operation, or alternatively can be readily adjusted betweenloading operations, is shown with reference to FIG. 2. Referring to FIG.2, elongated housing 16 of loader assembly 15 contains elongatedpassageway system 17 extending therethrough in direct open communicationwith the outside of housing 17 at rearward and forward housing ends 16'and 16" contains constricted cross section parts G and D as a throatportion, or section. Thus, passageway 17 comprises forward part D of anoverall throat portion, generally of circular cross section, formed asdescribed hereinafter; forward end section E diverging from theperiphery at the forward end d of throat part D toward and through theforward end 16" of housing 16, and rearward most section F divergingfrom rearward end c of throat part D for a predetermined distance towardhousing end 16 and then at substantially constant cross section throughhousing end 16. Rear section F of passageway 17 is more clearlyillustrated with reference to FIG. 2A which shows a rearward mostportion of loading assembly 15 including the entire passageway section Fextending rearwardly from throat part G through housing end 16; allparts shown in FIG. 2A being like parts of FIG. 2 and accordinglydesignated by the same index numbers.

Again referring to FIG. 2, bushing assembly 18, coaxially withinpassageway section F of housing 16 includes bushing member 19 andcollar-type member 21, annularly disposed in section F to form annulus23, forwardly extending from the forward end of bushing 19 toward, butshort of, closing contact with throat part D to form throat part G, and,together with throat part D, forming a resulting overall throat portionG plus D. Annular space 23 around collar member 21 is formed by theexterior wall of extended collar member 21 and an inner wall portion ofhousing 16. Spacing of collar member 21 from throat part D providesintermediate, and continuous open and unobstructed channelway 24 openingfrom annular space 23 into throat portion D and hence into anintermediate portion of the overall throat section, G plus D, entirelyabout the periphery thereof. The wall portions f and e formingchannelway 24 extend codirectionally, and often in substantiallyparallel relationship so as to angularly open channelway 24 into thethroat portion (G plus D) in a direction toward diverging end section E.In practice, wall portions f and e are formed by appropriate beveling ofthe walls of housing 16 and collar 21. as shown. Fluid inlet conduits 26extend from outside housing 16 through a sidewall thereof into directand open, fluidtight communication with annular space 23. Channelway 24opens into throat G plus D angularly and toward section E in the samemanner as described above with reference to conduits 12, FIG. 1.

Bushing member 19, which forms port section A is secured in fluidtightrelationship with housing wall 16 by suitable O- ring 27 and threads 22.The capacity of channelway 24, as a function of the width thereof isvaried, as desired, by threadably moving bushing assembly 19' axiallytoward or away from throat part D on seal 27.

Housing 16 is adapted to be threadably connected (threads 14') at thedownstream end with a suitable delivery conduit 28.

FIG. 3 is a perspective view of the loader assembly of the invention,and associated structure for operation on deck of a boat moving throughthe seismic test area, and is illustrated with specific reference to theloader assembly of FIG. 2 which is now preferred. All parts in FIG. 3,which are like parts of FIG. 2 are designated by the same but letteredindex numbers. Referring to FIG. 3, conduit, or hose, 25 connects withT-type manifold 29 for delivery of water pumped to the boat deck fromthe adjacent marine area. Manifold 29 connects at each end of the T witha conduit 26a each of which discharges into the reservoir 23a at pointsspaced apart about 180. Gauge 31 in line 25 records the pressure on themanifold, which in conjunction with the preset capacity of channelway24a continuously indicates the pressure of water delivered through thechannelway 240 into the throat (G plus D, FIG. 2). Housing 16a isthreadably connected at forward end 16"a via threads with deliveryconduit 280 leading to the underwater firing site.

In the operation of the loader assembly 15a water is pumped from theadjacent marine area via line 25 through manifold system 29 into lines26a, reservoir, or jacket 23a, channelway 24a and into and through thethroat and expansion section for discharge through conduit 28a. A smallcylindrical seismic charge assembly 37 (see FIG. 4) can be handinserted, or merely placed, in the rear, or port, section A'a of housing16a after which the charge assembly is driven into the rearward end ofthe throat (G plus D) under force of atmospheric air drawn intopassageway 17a through housing end l6'a. The charge assembly 37-isdriven into the throat past the ingress points of water from channelway24a and is then impinged by the moving high velocity water so that, withbenefit not only of the air pressure differential but also theadditional force of impingement, the charge assembly is driven throughthe throat into the diverging, or expansion chamber 17a for dischargeinto hose 28a for delivery to the shooting site.

As shown, there are no moving parts in the loading assembly and only oneoperator is required. Operation involves only the regulation of velocityof the water flow from channelway 24a into the throat and sequentialemplacement of the charges in the port section for rapid loading intothe conduit for delivery to the firing station If the water velocitythrough channelway 24 is relatively low the ratio of air to water inthroat portion G plus D is lower than when the flow velocity of waterinto the throat section is higher. At the higher air to water ratios theoperator need only insert the charge in the housing opening andsufficient suction force is available to promptly draw the charge intothe throat and cause it to travel rapidly for discharge into thedelivery hose. On the other hand when a low ratio of air to water isutilized, the force of suction is correspondingly lower and it is thengenerally necessary that the operator manually insert the charge intothe throat to a point closer to the zone of ingress of the water toaccomplish the desired loading rate.

A small seismic charge often loaded for delivery to the firing device,and fired. in accordance with the invention is in one embodiment, thatshown in FIG. 4 and disclosed in my parent application Ser. No. 818,475filed Apr. 21, 1969, referred to hereinabove; and which is a completepercussion initiatable assembly containing a delay fuse and a rim-firedrifle cartridge casing closure as the percussion sensitive portion.Referring to FIG. 4, primer assembly 34 extends into primer well 36 ofcomplete seismic charge assembly 37. In primer 34 elongated shell 38contains a high explosive charge 39 such as PETN, ad jacent closed end41. Ignition end 42 of shell 38 is closed by conventional rim-firedempty primed rifle cartridge casing 43 which includes end closure 44with charge 46 for rim firing, and casing portion 47; and the outsidediameter of casing portion 47 and the inside diameter of shell 38 areadjusted to provide an interference, or friction, fit of the casingclosure in the primer shell.

Confined ignition charge 46 is any suitable ignition composition whichignites to produce a flame in response to compression resulting frompercussion applied to the outer surface 47 of closure cap 44. Primerassembly 48 in shell 38 is any suitable assembly of primer composition,intermediate high explosive charge 39 and ignition charge 46, Delay fuseassembly 49 containing slow burning delay fuse composition 51 is of thetype conventionally used as a delay element in electric delay blastingcaps and is disposed intermediate the primer assembly 48 and ignition46. Delay composition 51 is ignitable in response to direct contact withflame emitted from ignition of charge 46 and is spaced in such ignitablerelationship therewith. The primer composition of assembly 48 isignitable (48') and detonatable (48") in response to heat and flameemitted from burning of delay fuse composition 51 and is disposedadjacent to delay fuse composition 51 in such igniting and detonatingrelationship therewith. High explosive charge 39 is detonatable inresponse to detonation of the primer charge of assembly 48 and isdisposed adjacent the assembly 48 in that detonating relationship.

Primer charge assembly 48 and base charge 39 are advantageously thoseutilized as such in the blasting cap art, exemplary of which are highexplosive base charges 39 including pentaerythritoltetranitrate,pentolite, RDX and the like, and primer charges such asdiazodinitrophenol, lead azide, and mercury fulminate. Exemplaryconfined ignition charge 46 components include potassium perchlorate,lead stiffnate, mercury fulminate, antimony sulfide and lead azide andmixtures of such materials as are well known in the munitions art, andare preferably those often utilized as a primer" charge in 0.22 caliberrifle cartridges. Delay fuse compositions 51 include those normallyutilized as such in the delay blasting cap art, those now preferredincluding lead oxide/boron, 98/2; read lead/boron, 98/2; bariumperoxide/telurium/selenium, 40/40/20; barium peroxide/selenium, 84/16;barium peroxide/tellurium, 60/40 and the like.

The primer assembly 48 in preferred practice comprises adiazodinitrophenol wafer 48' pressed above, and superposed, on elongatedcapsule 48" which extends within and is substantially coaxially withshell 38 in closing, or near closing relationship therewith. Capsule 48"is open at each end and is superposed on base charge 39 and contains asecond diazodinitrophenol charge 48" of density lower than that ofprimer wafer 48'. Wafer charge 48' is of sufficiently high density to beignitable in response to heat and flame from ignition of delay fusecomposition 51 and diazodinitrophenol charge 48 is of sufficiently lowdensity to be detonatable in response to heat developed by ignition ofwafer charge 48 to thereby in turn cause detonation of base charge 39.

Primer assembly 34 extends into well 36, percussion end 44 last, and itterminates in detonating contact with main charge 52 in cartridge shell53 of the complete assembly 37. Primer device 34 is preferably disposedentirely within shell 53 except to permit the primer end closure 44 atits outside surface 47 to be at least flush with the exterior surface ofwell 36 at the open end thereof and preferably to permit both the topsurface 47 and the ignition end 46 portions to protrude from well 34into the top recessed shell portion 54.

Recessed shell portion 54', formed by spacing shell top closure 54downwardly from topmost end, or rim 56 of shell 53 is optional but, byits extending wall members, provides protection against undue impact ofthe percussion sensitive portion of the cartridge assembly 37 duringhandling prior to shooting.

The primer element 34 is generally cylindrical and often is from about2% to about 3 inches in length by about 0.246 to 0.248 inch in diameter.

Further exemplary of a now preferred complete seismic charge assembly,including an NCN type main explosive charge, to be loaded for deliveryto the underwater firing site, in practice of the invention, is thatillustrated in the following list of specifications with particularreference to the assembly of FIG. 4.

psi. Below capsule (48)-Loose. Base charge 39, PETN, grams1.5 (pressedat 6,500 psi.)

Cartridge unit:

Metal shell 53-Cylindrical:

Length, inches-4.68 Diameter, inches:

Inside-2.04 Outside2.09 Recess 54, inches, length-0.41 NCN charge 52:

Weight, grams250 Length, inches-3.27 Diameter, inches2.04= Composition,wt. percent:

Ammonium nitrate-7 8.7 DNT-5.0 Fuel oil-l.5 Particulate aluminum-44.8

Pb/Sn is /15.

Exemplary of a suitable underwater firing device for receiving andfiring seismic charges loaded in accordance with the invention, is thatshown in FIG. 5 and disclosed and claimed in my copending parentapplication Ser. No. 818,475 above referred to; and further exemplary ofsuitable firing devices are a piston type assembly disclosed and claimedin the above referred to copending application Ser. No. 724,942. and animpact plate type assembly disclosed and claimed in the above referredto copending application Ser. No. 818,476.

Referring to FIG. 5, percussion initiated explosive charge assemblyconveyor conduit 55 of firing device 57 is threaded (threads 58) atrearward end 59 for connection with a suitable hose type deliveryconduit 28a (FIG. 3) for sequentially receiving elongated delayedpercussion initiatable seismic charge assemblies 37 (FIG. 4) fromdelivery hose 28a and then conveying them through forward end 61 forpercussion IIIIUKUOI'I.

Open guide-support means 62 is a suitable tray-type member adjacent andimmediately forward of conduit 55, and is in open communication anddirect alignment with conduit 55 for sequentially receiving the delaytype percussion initiatable seismic charge assemblies from conduit 55 asthey are moved axially therefrom; and for guiding each charge assemblyalong a path of continuous forward travel to wheel type contact. orfiring pin, means 63 at or near the forward end 62a of guide member 62.Guide member 62 is open for subsequent pivotal travel of the seismiccharge assembly, described further herein.

Although tray-type guide member 62 and conduit 55 can be connected inany suitable manner, they constitute in preferred practice a single unitof integral construction, as shown. Thus in the embodiment shown,conduit 55 and guide member 62 as an integral unit can be fabricated bycutting a relief from one end of a tube, or pipe, member along asuitable circumference say of from about 180 to 300. Regardless ofwhether conduit 55 and guide member 62 are of integral construction,guide member 62 is of shape and is secured to conduit 55 to sequentiallyreceive the axially moving seismic charge assemblies from conduit 55 andguide them in a line of continued forward travel, maintained under forceof fluid pressure in conduit 28a, toward wheel member 63. In a nowpreferred form, the inner wall 62b of guide member 62 is substantiallycoplanar with an adjacent inner wall portion of conduit 55 to facilitatetravel of the seismic charge assembly from conduit 55 onto guide member62.

Wheel member 63, in combination with guide member 62 is spaced from theforward end 61 of conduit 55 in a plane substantially codirectional withthe path of forward travel of the seismic charge assembly on guidemember 62; and is spaced from end 61 of conduit 55 so that the distanceof its rim portion closest to conduit 55 is greater than the length ofthe particular seismic charge assembly, say from 1.1 to 1.3 times thelength of the assembly, to provide a gap G between forward end 61 ofconduit 55 and the rearward end of the seismic charge assembly whenready for pivotal travel from guide member 62 as described hereinafter.

Wheel member 63 is rotatably supported at its hub by support pin 64.secured to end 66 of L-shaped bracket 67 of which one leg 67a extendsacross the forward end of guide member 62 and the other leg 67b extendsalong the exterior wall of guide member 62 and is secured thereto byscrew bolt members 68. Wheel member 63, when supported as abovedescribed, is disposed across the forward end of guide 62 sufficientlyto intercept the forward travel of the seismic explosive charge assemblyon member 62 and contact a portion of its rim, facing conduit 55, with apercussion sensitive portion of the charge assembly, for effectingpercussion initiation of the charge. Wheel 63 is advantageously ofdiameter sufficient for it to extend across the entire projected end ofconduit 55. However the total shadow area of wheel member 63 and itsassociated support structure including arm 67a, i.e. the total areafilled by that combined structure, is sufficiently limited to facilitatelinear flow of water, or other driving fluid from conduit 55, around itto facilitate guidance and support of the charge assembly along its pathof forward travel on guide member 62. Wheel member 63, and a percussionsensitive portion of the charge assembly are preferably positioned so asto be disposed in the central portion of the path of forward travel ofthe charge assembly. 1

Although the inside diameter of conduit 55 can be constant, it is oftenadvantageous that at least a rearward mostinner wall end portion thereofbe tapered in a forward direction to facilitate arrest and positioningof the charge assembly for conveying it to the guide member 62. Thetapered inner wall portion of conduit 55, when utilized, advantageouslyextends from rearward end 59 toward forward end 61 generally a distanceof from about one-fourth to one-half the length of conduit 55.

A now preferred embodiment of underwater seismic exploration systemutilizing a loading device of the invention, as a component, isdiagrammatically illustrated with reference to FIG. 6. Referring to FIG.6, charge assembly storage 69, on deck 71 of tow boat 72 provides forstorage of percussion initiatable charge assemblies such as of FIG. 4.Charge assemblies from storage 69 are sequentially inserted in a loaderassembly of the invention and can be adapted for electrical ornonelectrical firing, as desired, which in turn determines theparticular firing mechanism utilized at the firing station. However apercussion initiatable type assembly such as illustrated with referenceto FIG. 4 is now preferred in conjunction with a firing device forpercussion firing the charge underwater, such as that of FIG. 5. Thus,percussion initiatable charges 37 (FIG. 4) are sequentially inserted,percussion sensitive end first, into passageway 17a of loader assembly15a (FIG. 3) through the port section A'a concurrently with flow ofwater pumped by pump 73 from the adjacent body of sea water 74 via line76 and discharged via line 25 and manifold 29a into annular reservoir,or jacket, 23a (FIG. 3) at points 78a and 78b, apart, for discharge athigh velocity via channelway 240 (FIG. 3) into the throat section (Gplus D, FIG. 2). Charges 37 are thus, by force of air enteringpassageway 17a through the port end under atmospheric pressure, drawninto the throat section and into impinging relationship with the highvelocity flowing water; and with additional force of resultingimpingement they are moved into and through diverging,or expansion, endsection Ea (FIG. 3) under accompanying increased pressure and intodelivery conduit 28a (FIG. 3) for delivery to the underwater site forpercussion initiation upon contact with the wheel assembly 63 (FIG. 5)and delayed firing outside the system for generation of seismic energy.

Thus, flexible hose 280 extends from the loader 15a to the firingmechanism 57 (FIG. 5) for sequential delivery of the percussioninitiatable charges and firing, as the firing device is towed by boat 72through the marine seismic area.

Streamer cable assembly 79, of conventional design, comprises ahydrophone cable 81 containing a plurality of hydrophone groups 82integrally connected in spaced apart relationship along the entirelength thereof, and is connected to one end by tow cable 83 to reelassembly 84 on the boat deck for reeling and towing. Suitable well knownmeans (not shown) are associated with streamer cable assembly 79 tostabilize its position at a predetermined depth in the body of water;and suitable means (not shown) for communicating hydrophone groups 82with recorder means on the boat deck, extend from within cable 81 alongside tow cable 83 via reel assembly 84.

In practice, streamer assembly 79 is towed through the water body duringwhich time the seismic charges are detonated outside the system atpredetermined intervals, and distances, to initiate seismic shock at thepredetermined points in the test area. Disturbances produced by theshot, or shock, are detected by the hydrophone groups which convertthose pressure variations into electric signals which are thencommunicated to the boat for recording.

By way of further illustration of the system of the invention, a seriesof charges of FIG. 4 were sequentially loaded in a loading device ofFIG. 2 when utilized as a component of a system of FIG. 6, associatedwith the auxiliary equipment shown in FIG. 6. The pressure diflerentialbetween the outside of the loader and the throat section therein wasabout 14 p.s.i. At that high pressure differential, each charge wasmerely laid in the open port area of the loader, i.e. in end section 17'of passageway 17 (FlG. 2), as illustrated with reference to FIG. 3. andreleased. The force of air initially flowing under atmospheric pressurerapidly moved the seismic charges into the throat section; and, inconjunction with impingement action of posite side 93 extendingsufficiently from housing end 16' to contain support point 87.Suspension cord 88 is secured at one end to bracket side 93, at point 87and at the other end to sphere 86 by any suitable nut type fastenermeans 95 and 94 the high velocity water entering the throat through theChan 5 respectively. ne ay 24. the c g c rdingly mo ed into and through.In the operation of the sphere closure of FIG. 7, the operathe expansionmember E into the hose 28 for delivery to the tor, during the nonloadingperiod with concurrently continued underwater finng (iii 6 57 of FIG 6at a depth of about 36 operation f h water pumping System, id h ll feeLTwenty Ven mdlflduai 9 i q f Shots member into peripheral closingrelationship with port A, and were made, without a failure, within aperiod Of 9 min e y the force of suction draws the sphere into closingposition with oneoperator positioned at the loading station tosequentially the port opening to terminate air flow into the port andfeed the charges the port for the loadmg' thereby preclude flow of airto the underwater shooting site. The following, further illustrative ofthe invention, is a tabu- W loading '15 to be resumed, the p ato gr psthe ll lation of various component dimensions of the loader as- 5 m m raway from the port to open the port for sequential sembly of HO. 2utilized in the above series of tests: loading of the charges. Thesphere handling cycle is then re- Angle of di- Inches vergence from thelon- Length Diameter Width gitudinal housing axis Housing 16 (circularcross section at outer periphery) i. 18. 5 5 (o.d.) 7 Throat (G plus1))- Part G 2.625 2. 250 Part i), 2.200 2.250 Diverging Section E 12.0145( At end 17' 3. 0 At throat and d 2. Channelway 24:

Housing wall e Housing wall I Variable opening 0 from annulus Variableopening it into throat G pl Variable minimum 1' Port A:

At opening 17 At throat end a Conduits 2G Annulus 23:

Inlet side I:

1 Excluding channel opening h, which is a part of throat part G, butvariable and described below.

In the operation of the loader assembly of the invention as it is towedthrough a seismic marine area, it is often advantageous from theoperational standpoint to permit continuous flow of water into andthrough the loader assembly for discharge into the shooting areaindependently of whether charge loading is in progress. in this mannerthe need for operating steps involving alternate starting and stoppingthe water pumping system between loading periods is eliminated. However,during such nonloading periods there is often a resulting accumulationof air bubbles at the discharge end of the system, i.e. in theunderwater shooting area, which, in some instances, may impairmeasurement. of seismic disturbances resulting from subsequent shots.

lt is therefore sometimes advantageous that flow of air to the loaderdevice be eliminated,.or substantially reduced, during any nonloadingperiod of continued water flow, which can be accomplished by anysuitable means.

One such means is illustrated with reference to H6. 7 which shows asection of the loader device of FIG. 2, including port section A, and aball type assembly for closure of the port to eliminate flow of air intoand through the loader device to the underwater shooting site in thoseinstances in which operation of the water pumping system is continuedduring a nonloading period. All like parts of FIGS. 2 and 7 aredesignated by the same index numbers.

Referring to FIG. 7, elastomeric sphere, or ball, 86, outside housing 16and having a diametric cross section greater than that of circular portopening 17', is suspended from an external point 87 by suspension cord88 so as to be in position for travel along an are having support point87 as a center, into and out of peripheral closing contact relationshipwith the passageway 17 at rearward opening 17'. Any suitable means forsuspending sphere 86 can be utilized, such as a U-bracket 89, with openend 91 facing toward housing end 16', secured at one side 92 to theouter wall of housing 16, with the oppeated to close the port duringnonloading and to open it for loading without the need for terminatingoperation of the water pumping system. What I claim and desire toprotect by Letters Patent is:

I claim:

1. A device for loading seismic explosive charges for delivery to anunderwater shooting site comprising a housing; a passageway extendingthrough said housing for successively conveying said charges, and saidpassageway having a constricted cross section along part of its length,as a throat portion; a section of said passageway diverging from saidthroat portion; and means for conveying fluid into said throat portionand for passing same through said throat portion under high velocityconditions in a direction toward said diverging section.

2. in a loading device of claim 1, said diverging section constitutingan end portion of said passageway.

3. In a loading device of claim 2, said throat portion disposedintermediate the ends of said passageway, and an opposite end section ofsaid passageway extending from said throat portion as a port section forreceiving said charges for delivery into said throat.

4. A loading device of claim 3 wherein said port section diverges alongat least part of its length from said throat portion.

5. In a loader device of claim 4, at least one conduit opening through asidewall of said housing into direct fluidtight communication with saidthroat portion, as said means for conveying said high velocity fluid.

6. In a loader device of claim 5, a plurality of said conduits openinginto said throat at points spaced along a peripheral path on the innerwall of said housing.

7. In a device of claim 6, a pair of said conduits for conveying fluidinto said throat po 'tion, opening into said throat at substantiallyequal-spaced points.

8. ln a loading assembly of claim 5, a bushing member coax ially withinsaid housing at the port end thereof in fluidtight relationship with theinner housing wall, and forming said port section; said throat portionbeing formed by separate parts ineluding, as a first part, a section ofsaid constricted cross section adjacent said diverging end section; acollar member annularly extending within said passageway from saidbushing in fluidtight relationship therewith, in axial alignment withsaid first throat section as the remaining part of said cross sectionbut short of direct contact therewith, thereby fonning an openunobstructed channelway into said throat portion from the entire annulusformed around said collar.

9. in a loader assembly of claim 8, said bushing and collar memberconstituting an integral unit of construction, at least one of saidconduits opening into said annulus, and means for moving said unitaxially within said housing for adjustment of the dimension of saidunobstructed passageway.

10. A system for loading seismic charges for delivery to an underwaterfiring station which comprises a charge loading station remote from saidfiring station, and a seismic explosive charge loader assembly at saidloading station; said loader assembly comprising l a housing, (2) apassageway extending through said housing for successively conveyingsaid charges, and said passageway having a constricted cross sectionalong part of its length, as a throat portion, (3) a section of saidpassageway diverging from said throat portion, (4) means for conveyingfluid into said throat portion and to passing same through said throatportion under high velocity flow conditions in a direction towardsaiddiverging section, and (5) means for communicating said passagewaythrough said diverging section with conduit means for deliveringexplosive charges from said loader assembly to said firing station; andmeans for delivering water, as said fluid, through said conveying meansfor said flow through said throat.

11. A system of claim wherein said diverging section constitutes an endportion of said passageway; said throat portion is disposed intermediatethe ends of said passageway; an opposite end section of said passagewayextends from said throat portion as a port section for receiving saidcharges for delivery into said throat; and at least one conduit openingthrough a sidewall of said housing into direct fluidtight communicationwith said throat portion, as means for conveying said high velocityfluid.

12. in a system of claim 11, a bushing member coaxially within saidhousing at the port end thereof in fluidtight relationship with theinner housing wall, and forming said port section; said throat portionbeing formed by separate parts including, as a first part, a section ofsaid constricted cross section adjacent said diverging end section; acollar member annularly extending within said passageway from saidbushing in fluidtight relationship therewith, in axial alignment withsaid first throat section as the remaining part of said cross sectionbut short of direct contact therewith, thereby fonning an openunobstructed channelway into said throat portion from the entire annulusformed around said collar, and at least one of said conduits openinginto said annulus.

13. A method for sequentially loading seismic explosive charges at acharge loading station for delivery to an underwater seismic shootingsite, which comprises pumping water from a marine area at high velocitythrough a throatway supported at said station in direct communication atone end with atmospheric air, and then passing said water into andthrough a diverging zone of expansion, whereby the pressure in saidthroat becomes less than that of the surrounding atmospheric air and airis drawn from the adjacent atmosphere into said throat through said openend; sequentially inserting said charges from the adjacent airatmosphere into said open end of said throat-way, whereby said chargesare moved into an initial zone in said throat-way by force of air drawnfrom the adjacent air atmosphere and then through the remainder of saidthroat-way and through said diverging zone under combined force ofatmospheric pressure and impinging force of said water for delivery,entrained in said water, to said shootin site.

%4. in a method of claim 13, pumping said water into an intermediatezone in said throat-way and then passing said water through theremainder of said throat-way for travel through said diverging zone.

15. In a method of claim 14, pumping said water into said throat-way ata plurality of points.

16. In a method of claim 15' pumping said water into said throat-way ata plurality of substantially equispaced points.

17. A system for generating seismic energy in an underwater seismic testarea utilizing small explosive charges as the seismic energy source,comprising a submersed firing station for firing said charges; a seismiccharge loader device remote from said firing station and comprising (1)a housing (2) a passageway extending through said housing forsuccessively conveying said charges, and said passageway having aconstricted cross section along-part of its length, as a throat portion,(3) a section of said passageway diverging from said throat portion, and(4) means for conveying fluid into said throat portion and for passingsame through said throat portion under high velocity flow conditions ina direction toward said diverging section; means for delivering fluidthrough said conveying means for said high velocity flow; conduit meansconnecting the diverged end of said diverging section of said passagewaywith said firing station for conveying said charges from said loaderdevice to said firing station; and means at said firing station, forfiring said charges to provide said seismic energy.

18. In a system of claim 17 means for measuring said seismic energy fora seismic record.

19. A method for sequentially loading seismic explosive charges at acharge loading station in a marine area and delivery of the charges toan underwater shooting site and firing same to provide seismic energywhich comprises pumping water from the marine area at high velocitythrough a throatway supported at said station in direct communication atone end with atmospheric air, and then passing said water into andthrough a diverging zone of expansion, whereby the pressure in saidthroat becomes less than that of the surrounding atmospheric air and airis drawn from the adjacent atmosphere into said throat through said openend; sequentially inserting said charges from the adjacent airatmosphere into said open end of said throat-way, whereby said chargesare moved into an initial zone in said throat-way by force of air drawnfrom the adjacent air atmosphere and then through the remainder of saidthroat-way and through said diverging zone under combined force ofatmospheric pressure and impinging force of said water for delivery,entrained in said water, to said shooting site; delivering said chargesfrom said diverging zone to said shooting site, and then firing saidcharges to provide said seismic energy.

20. in a method of claim 19 measuring said seismic disturbances toprovide a seismic record.

21. in a device of claim 1, means for closing said passageway at the endthereof opposite said diverging section, during a nonloading period, inresponse to force of suction generated by said passing of fluid throughsaid throat section.

22. in a device of claim 21, an elastomeric sphere, as said closingmeans, outside said housing and facing a circular port inlet of saidpassageway, and having a diametric cross section greater than that ofsaid port inlet; and said sphere suspended so as to travel along an arcwith the point of suspension as the center, into and from peripheralclosing contact relationship with said port inlet.

May 11, 1971 U.S.P. 3.578. Dated Patent No.

Inventor-(s) Richard R. Larson (Case 2-3) It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Col. 1, Line 55 & 56 of p.p. Page 3, Line 16 of spec.

"and now Pat. No. 3, 509,820" should appear after second occurenceof"April 21, 1969" Signed and sealed this 31st day of August 1971.

(SEAL) Attest:

EDWARD M.FLE'I'CHER,JR. Attesting Officer WILLIAM E. SGHUYLER,J'R.Commissioner of Patents

1. A device for loading seismic explosive charges for delivery to anunderwater shooting site comprising a housing; a passageway extendingthrough said housing for successively conveying said charges, and saidpassageway having a constricted cross section along part of its length,as a throat portion; a section of said passageway diverging from saidthroat portion; and means for conveying fluid into said throat portionand for passing same through said throat portion under high velocityconditions in a direction toward said diverging section.
 2. In a loadingdevice of claim 1, said diverging section constituting an end portion ofsaid passageway.
 3. In a loading device of claim 2, said throat portiondisposed intermediate the ends of said passageway, and an opposite endsection of said passageway extending from said throat portion as a Portsection for receiving said charges for delivery into said throat.
 4. Aloading device of claim 3 wherein said port section diverges along atleast part of its length from said throat portion.
 5. In a loader deviceof claim 4, at least one conduit opening through a sidewall of saidhousing into direct fluidtight communication with said throat portion,as said means for conveying said high velocity fluid.
 6. In a loaderdevice of claim 5, a plurality of said conduits opening into said throatat points spaced along a peripheral path on the inner wall of saidhousing.
 7. In a device of claim 6, a pair of said conduits forconveying fluid into said throat portion, opening into said throat atsubstantially equal-spaced points.
 8. In a loading assembly of claim 5,a bushing member coaxially within said housing at the port end thereofin fluidtight relationship with the inner housing wall, and forming saidport section; said throat portion being formed by separate partsincluding, as a first part, a section of said constricted cross sectionadjacent said diverging end section; a collar member annularly extendingwithin said passageway from said bushing in fluidtight relationshiptherewith, in axial alignment with said first throat section as theremaining part of said cross section but short of direct contacttherewith, thereby forming an open unobstructed channelway into saidthroat portion from the entire annulus formed around said collar.
 9. Ina loader assembly of claim 8, said bushing and collar memberconstituting an integral unit of construction, at least one of saidconduits opening into said annulus, and means for moving said unitaxially within said housing for adjustment of the dimension of saidunobstructed passageway.
 10. A system for loading seismic charges fordelivery to an underwater firing station which comprises a chargeloading station remote from said firing station, and a seismic explosivecharge loader assembly at said loading station; said loader assemblycomprising (1) a housing, (2) a passageway extending through saidhousing for successively conveying said charges, and said passagewayhaving a constricted cross section along part of its length, as a throatportion, (3) a section of said passageway diverging from said throatportion, (4) means for conveying fluid into said throat portion and topassing same through said throat portion under high velocity flowconditions in a direction toward said diverging section, and (5) meansfor communicating said passageway through said diverging section withconduit means for delivering explosive charges from said loader assemblyto said firing station; and means for delivering water, as said fluid,through said conveying means for said flow through said throat.
 11. Asystem of claim 10 wherein said diverging section constitutes an endportion of said passageway; said throat portion is disposed intermediatethe ends of said passageway; an opposite end section of said passagewayextends from said throat portion as a port section for receiving saidcharges for delivery into said throat; and at least one conduit openingthrough a sidewall of said housing into direct fluidtight communicationwith said throat portion, as means for conveying said high velocityfluid.
 12. In a system of claim 11, a bushing member coaxially withinsaid housing at the port end thereof in fluidtight relationship with theinner housing wall, and forming said port section; said throat portionbeing formed by separate parts including, as a first part, a section ofsaid constricted cross section adjacent said diverging end section; acollar member annularly extending within said passageway from saidbushing in fluidtight relationship therewith, in axial alignment withsaid first throat section as the remaining part of said cross sectionbut short of direct contact therewith, thereby forming an openunobstructed channelway into said throat portion from the entire annulusformed around saiD collar, and at least one of said conduits openinginto said annulus.
 13. A method for sequentially loading seismicexplosive charges at a charge loading station for delivery to anunderwater seismic shooting site, which comprises pumping water from amarine area at high velocity through a throat-way supported at saidstation in direct communication at one end with atmospheric air, andthen passing said water into and through a diverging zone of expansion,whereby the pressure in said throat becomes less than that of thesurrounding atmospheric air and air is drawn from the adjacentatmosphere into said throat through said open end; sequentiallyinserting said charges from the adjacent air atmosphere into said openend of said throat-way, whereby said charges are moved into an initialzone in said throat-way by force of air drawn from the adjacent airatmosphere and then through the remainder of said throat-way and throughsaid diverging zone under combined force of atmospheric pressure andimpinging force of said water for delivery, entrained in said water, tosaid shooting site.
 14. In a method of claim 13, pumping said water intoan intermediate zone in said throat-way and then passing said waterthrough the remainder of said throat-way for travel through saiddiverging zone.
 15. In a method of claim 14, pumping said water intosaid throat-way at a plurality of points.
 16. In a method of claim 15pumping said water into said throat-way at a plurality of substantiallyequispaced points.
 17. A system for generating seismic energy in anunderwater seismic test area utilizing small explosive charges as theseismic energy source, comprising a submersed firing station for firingsaid charges; a seismic charge loader device remote from said firingstation and comprising (1) a housing (2) a passageway extending throughsaid housing for successively conveying said charges, and saidpassageway having a constricted cross section along part of its length,as a throat portion, (3) a section of said passageway diverging fromsaid throat portion, and (4) means for conveying fluid into said throatportion and for passing same through said throat portion under highvelocity flow conditions in a direction toward said diverging section;means for delivering fluid through said conveying means for said highvelocity flow; conduit means connecting the diverged end of saiddiverging section of said passageway with said firing station forconveying said charges from said loader device to said firing station;and means at said firing station, for firing said charges to providesaid seismic energy.
 18. In a system of claim 17 means for measuringsaid seismic energy for a seismic record.
 19. A method for sequentiallyloading seismic explosive charges at a charge loading station in amarine area and delivery of the charges to an underwater shooting siteand firing same to provide seismic energy which comprises pumping waterfrom the marine area at high velocity through a throat-way supported atsaid station in direct communication at one end with atmospheric air,and then passing said water into and through a diverging zone ofexpansion, whereby the pressure in said throat becomes less than that ofthe surrounding atmospheric air and air is drawn from the adjacentatmosphere into said throat through said open end; sequentiallyinserting said charges from the adjacent air atmosphere into said openend of said throat-way, whereby said charges are moved into an initialzone in said throat-way by force of air drawn from the adjacent airatmosphere and then through the remainder of said throat-way and throughsaid diverging zone under combined force of atmospheric pressure andimpinging force of said water for delivery, entrained in said water, tosaid shooting site; delivering said charges from said diverging zone tosaid shooting site, and then firing said charges to provide said seismicenergy.
 20. In a method of claim 19 measuring said seismic disturbancesto provide a seismic record.
 21. In a device of claim 1, means forclosing said passageway at the end thereof opposite said divergingsection, during a nonloading period, in response to force of suctiongenerated by said passing of fluid through said throat section.
 22. In adevice of claim 21, an elastomeric sphere, as said closing means,outside said housing and facing a circular port inlet of saidpassageway, and having a diametric cross section greater than that ofsaid port inlet; and said sphere suspended so as to travel along an arcwith the point of suspension as the center, into and from peripheralclosing contact relationship with said port inlet.